1. Field of the Invention
This invention relates to a treatment apparatus utilizing microwave discharge plasma, and more particularly an apparatus for treating powdery materials by use of microwave plasma.
2. Discussion of Related Art
There is generally known a process in which a powdery material is treated as by using an electric furnace to convert it into or synthesize a chemical material. In the electric furnace, the powdery material to be treated is externally heated in an atmosphere of reaction gas to cause the material to react with the reaction gas. Such a process is, however, disadvantageous in that a large amount of thermal energy is lost from the heating furnace thus reducing the thermal efficiency, a large amount of reaction gas is consumed and it is difficult to uniformly treat the powdery material.
Another process is also known in which powdery materials are treated by use of a torch of high-pressure plasma. This process also has disadvantages in that a large amount of reaction gas is consumed and that it is difficult to produce a plasma in its stable state.
If microwave discharge plasma is used to treat powdery materials in distinction to the above processes, energy efficiency would be increased and also a decreased amount of reaction gas would be required. Where powdery materials are treated by use of plasma, especially microwave discharge plasma, however, a stream of plasma observed as a kind of blast (plasma blast) is formed in the plasma reaction area for unknown reason. The prior art apparatus utilizing the microwave discharge plasma is so designed that a reaction tube is horizontally disposed to supply it with reaction gas and plasma laterally of the tube. Therefore, the powdery materials to be treated may be blown off downstream by the plasma blast in the reaction tube so that the amount of treated material to be recovered is decreased. Moreover, a separate agitating means must be provided for realizing a uniform treatment. This results in a treatment apparatus having a complicated structure. Furthermore, it is desirable that the treatment efficiency can be increased by using a continuous treatment process in which an amount of treated powder is being removed while the same amount of powder to be treated is being supplied. It is, however, difficult to realize such a continuous treatment process in the prior art treating apparatuses. If realized, they have reduced treatment efficiency.